Understanding Glucose Spikes: Should You Be Concerned?
A lot of people are starting to worry about how glucose spikes might impact their health, as this has been a popular topic on social media. Let’s take an evidence-based look at this.
What are glucose spikes?
A glucose or blood sugar spike occurs when there is a fast temporary rise in blood glucose levels after eating.
When we eat foods containing carbohydrates, such as bread, pasta, rice or potatoes, our body breaks down the carbs into sugar molecules called glucose. These glucose molecules are then released into the bloodstream, causing our blood sugar levels to rise. This triggers the pancreas to release insulin, a hormone that helps the body use and store glucose for energy.
This is a completely normal physiological response that can happen for a number of other reasons too, such as (1, 2, 3, 4):
Consuming fat, protein or caffeine (so not just carbs!)
Stress
Dehydration
Illness, injury or sunburn
Certain types of high-intensity exercise
Hormonal changes across the menstrual cycle
Which foods cause glucose spikes?
Although foods that contain protein, fat or carbs can all contribute to glucose spikes, it’s carbs that have the biggest impact. The glycemic index (GI) is a measure of how quickly foods containing carbohydrates raise our blood sugar levels. Foods with a high GI score (70 or above) are digested quickly and cause a rapid increase in blood sugar levels, while foods with a low GI score (55 or below) are digested more slowly and cause a more gradual increase in blood sugar levels.
Examples of high GI foods:
Sugary food and drinks
White bread
White rice
Potatoes
Examples of low and medium GI foods:
Meat, chicken, fish and eggs
Dairy (unflavoured/unsweetened)
Non-starchy vegetables like broccoli, spinach, cauliflower, etc.
Most whole fruit
Oats
Pasta (white or wholemeal)
Basmati rice
Beans, peas and lentils
But focusing on GI alone isn’t recommended, as this doesn’t tell us how nutritious a food is and blood glucose response is influenced by so many factors (3, 5, 6):
Cooking methods
How ripe food is
The amount and combination of food consumed
Individual genes and physiology — two different people can respond very differently to the same meal or situation
The time of day — tends to be most efficient in the morning
Health conditions like diabetes and PCOS
Meal pattern — e.g. skipping breakfast may increase glucose spikes later in the day
How well-rested you are
Food choices can also help with lowering glucose spikes. For example, adding foods that contain fibre, fat and protein to those containing higher GI carbs, slows down absorption of carbs which leads to less of a glucose spike (5). This is also a nutritious and balanced way of putting meals and snacks together.
Should you worry about glucose spikes?
As already highlighted in this article, an increase in blood glucose levels is an entirely normal physiological response. This means that your body is functioning and digesting carbs to be used as energy, and this can happen for a number of other reasons as well.
However, if glucose spikes are very frequent or remain high for long periods of time this can damage blood vessels and other tissues, increasing the risk of complications to the eyes, heart, kidneys and nerves (7).
But this is most likely to occur in those who have conditions like diabetes or insulin resistance when glucose spikes can occur more frequently and be more severe. Symptoms of chronically high blood glucose levels would also be present — like peeing a lot, extreme thirst and fatigue, blurry vision or losing weight.
It’s important to mention that the opposite extreme, low blood glucose levels, is also a problem as this can lead to issues such as confusion, drowsiness, blurred vision, slurred speech and in more extreme cases, seizures, coma or even death (8). Again, this is most likely to occur where there is a medical issue with controlling blood glucose levels such as diabetes.
So it’s clear that monitoring and managing blood glucose levels is important when it comes to diabetes, but what about those who don’t have this medical condition?
Although this is becoming more popular, there is currently very little evidence to back this up and it isn’t routinely advised by healthcare professionals at the moment (9). The pros and cons need to be weighed up on an individual level, as although it may be useful for some people to learn how their blood glucose levels respond to certain foods or situations, or for spotting issues with insulin responses early, for others this could do more harm than good if it becomes obsessive and damaging to their relationship with food.
Overall, having some awareness of how food and lifestyle choices can help with keeping blood glucose levels stable can be helpful for health and maintaining stable energy levels. But unless you have a medical reason to do so, the recent trend of obsessing over managing glucose spikes may do more harm than good.
Top tips for supporting stable blood glucose levels
Eat regularly without big gaps in the day (i.e. every 2-4 hours)
Consume balanced meals most of the time that contains carbs, protein, fibre and fat
Adding protein, fibre or fat to a high GI snack will reduce the glucose spike (e.g. adding peanut butter to white toast)
Movement, stress management and sleep all help with maintaining healthy glucose levels
Attend medical appointments and check-ups and speak with your doctor if you are worried about possible high or low blood glucose levels
References
Paterson, M., Bell, K. J., O’Connell, S. M., Smart, C. E., Shafat, A., & King, B. (2015). The role of dietary protein and fat in glycaemic control in type 1 diabetes: implications for intensive diabetes management. Current diabetes reports, 15, 1-9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4512569/
American Diabetes Association. (2018). Good to know: factors affecting blood glucose. Clinical Diabetes, 36(2), 202-202. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5898168/
Centers for Disease Control and Prevention. (2022). 10 Surprising Things That Can Spike Your Blood Sugar. https://www.cdc.gov/diabetes/library/spotlights/blood-sugar.html
American Diabetes Association Website “Why Does Exercise Sometimes Raise Blood Glucose (Blood Sugar)?” https://diabetes.org/healthy-living/fitness/why-does-exercise-sometimes-raise-blood-sugar
Diabetes UK Website “Glycaemic Index and Diabetes” https://www.diabetes.org.uk/guide-to-diabetes/enjoy-food/carbohydrates-and-diabetes/glycaemic-index-and-diabetes
NHS Website “What is the Glycaemic Index (GI)?” https://www.nhs.uk/common-health-questions/food-and-diet/what-is-the-glycaemic-index-gi/
Mouri, M., & Badireddy, M. (2022). Hyperglycemia. In StatPearls [Internet]. StatPearls Publishing. https://pubmed.ncbi.nlm.nih.gov/28613650/
American Diabetes Association Website “Hypoglycemia (Low Blood Glucose)” https://diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hypoglycemia
Holzer, R., Bloch, W., & Brinkmann, C. (2022). Continuous glucose monitoring in healthy adults—possible applications in health care, wellness, and sports. Sensors, 22(5), 2030. https://www.mdpi.com/1424-8220/22/5/2030
